Our story is this:
The location: Murrumbateman, New South Wales
The land: 6500 square metre block (land due to settle in January 2022) - north facing, approximately 54 metres wide by 120 metres deep
The people: Myself and the wife with plans for a family
The brief: A solar passive home built using conventional construction techniques
The builder: Classic Constructions
The background: My wife and I made the fairly impulsive decision to buy a block of newly released land in a new estate at Murrumbateman, NSW, in October 2020. We had no immediate plans to buy, and certainly had no plans to build. But we had the funds (mostly) and a keen eye on the Canberra property market. There wasn't much coming up in Canberra that we liked in terms of established houses, and then one day she saw an online ad for land that was releasing soon. I had the day off work, so I went out to take a look, and on a splendidly peaceful and rainy day I fell in love with the area immediately. We bought a block a day or two later and essentially had our pick of the lot. Our block should sit nice and high, is north facing, and should have a nice view to the hills on the horizon.
The obsession: I've always had a keen interest in architecture and design and I was immediately obsessed with house plans. In earnest, we started looking around at a few builders. We went to a seminar with a volume builder, Regal Homes, and their designer told us all about the benefits of solar passive design. After that, I was like Alice down the rabbit hole. Lots of research, scrolling through thousands of plans on pinterest for inspiration, and drawing, drawing, drawing.
Building solar passive just makes sense. If you're planning a new house and don't at least cast your mind toward a few of the very simple principles it utilises, you're robbing yourself of the opportunity to live in a thermally comfortable, energy efficient house without having to do anything too out of the ordinary.. Particularly (as in our case) where you've got a large rural block and the freedom to place your house as you please.
What I learned:
I appreciate there's a lot more to it than this, but the key solar passive principles I was applying when coming up with our plans were essentially these:
- North light is king - minimise or eliminate east and west windows as much as possible, keep smaller windows on the south side, and use tons of glazing on your north side
- This means getting as many of your main living areas to the north of your plan as possible, and sticking the lesser used or more utility type rooms like the laundry to the south
- Orient the house as best you can toward solar north, not magnetic north
- High thermal mass in places the winter sun will filter through to - e.g. polished or burnished concrete floors in those northern living spaces, strategic brick walls placed inside
- Deeper eaves on the north side, calculated to completely block out the higher summer sun, but which allow all the lower winter sun to penetrate your north glazing and heat up those high thermal mass features inside
- Those high thermal mass features store heat from the sun from during the day and release it all back into the house during the cool of the night
- Try to allow for good cross-ventilation, particularly of your living spaces
- Good air tightness is critical - you don't want to be airtight to Passive House (aka PassivHaus) standards, which would require the house to be mechanically ventilated. But you DO want a builder that understands where leakage occurs and realises the importance of sealing properly around windows, square set cornices, avoiding penetrations in the ceiling etc.
At this stage, I want to give a shout out to yourhome.gov.au. This was in invaluable resource for learning everything an amateur could possibly need to know about building a solar passive house (particularly with regard to calculating the depth of those eaves).
I also want to mention The Booken House on Instagram. This is an example that takes the solar passive idea to the extreme, but is a perfect illustration of what can be achieved using conventional construction techniques (and therefore on a normal reasonable budget). Her results also appear to be quite amazing, and were quite inspirational for me.
The plan:
Over time I taught myself how to use SketchUp, which is a brilliant free to use CAD program, and used that for most of my many, many plan iterations. Shout out as well to Home By Me, which is a free interior design program that was great for drawing basic plans and awesome for furniture mapping (it also does neat 3D rendering of spaces).
Below is what I eventually came up with and is what we've submitted to the builder's architect. It closely considers not only the above principles but also how we live our lives and how we anticipate living them in the future. We've told the architect to change anything he sees fit, but he told us it was a nicely resolved plan and only suggested a few things:
- Rejigging the front a little to get more morning light into the kitchen
- Moving the powder room toward the mudroom/laundry (a great idea for when doing yard work, or if we eventually put in a pool)
- Widening the study and window seat section between the living and bedroom pavilions
- Consider moving the garage to the west side (this would be ideal as it would mean it absorbs the hot afternoon sun, rather than the sun directly striking the side of the house. However, the fall of our site would mean it would need to go on the front of the house, which is IMO a waste of some of our northern frontage, and I'm also keen to hide it around the side of the house because I think garages aren't all that nice to look at, PLUS our gate is on the eastern end of our front boundary - so it'll stay to the east)
- Roofline changes - roofs are really hard to do in sketchup so a few of them were drawn flat just due to my own limitations with the program
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The above plan takes inspiration from heaps of different plans. I realised pretty quickly the ideal block is actually probably one that faces south, because there are SO MANY awesome plans with living spaces all oriented to the backyard of houses that are designed for south street frontages (mainly for privacy reasons, I suppose). For houses that face north and have northern views, it was incredibly challenging to find anything that worked. Hence my struggle to come up with something unique.
Important to note:
- Polished/burnished concrete in all north facing rooms, carpets for comfort in the southern bedrooms
- Heaps of north glazing (the architect also pointed out it can be possible to have too much glazing even with solar passive designs and there is a ratio of glazing to floor space that should be adhered to - although its a trade off, because aesthetically, more glazing looks more amazing)
- Only one west-facing window (small, in the bathroom)
- Zero east facing windows - only the entry door
- Cross-ventilated living pavillion
- We're planning on installing a 6.6kw PV solar system to take care of most of our power needs
- Having a good level of air tightness is super important (not to PassivHaus standards of course, or to the point where you'd need mechanical ventilation, but reducing air leaking is critical). The builder we've chosen prides themselves on their attention to detail during construction and, for example, uses high R-Value insulation as standard. They understand that I want to avoid unnecessary penetrations in the ceiling such as downlights or ducts for air conditioning, as in most conventional homes these are the sorts of things that contribute to massive heat loss.
There are loads of reasons from a lifestyle perspective the plan has been designed the way it has, but I'll mention only a few:
- We love the dual pavillion style (one for living and master bedroom, and the second which can be closed off for heating efficiency and noise related reasons, intended for guests and our eventual children)
- We wanted a place that was large enough to be in-keeping with the big family homes in the area, but not huge. This is because we like a cosier feeling home, and bigger homes are less energy efficient and more expensive to build. This plan has only roughly 230m2 of living space, so it's by no means a monster, and would probably be considered quite small for the area. We think it strikes a good balance.
Here's some sketchup renders of a slightly earlier iteration of the above plan. This is to give an idea of the scale of glazing I want to achieve and the materials we like:
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Sketchup is also amazing because it has allowed me to model the shadows on the house in winter verses in summer. This has given me a lot of confidence that the place won't overheat in summer, because as you'll see, those eaves are putting in work and completely shading the glazing in summer.
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1:00pm on summer solstice
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1:00pm on winter solstice
So, in the dead of winter, we should have sunlight galore streaming in and heating up that concrete slab and internal brickwork, to be slowly released overnight. In summer, we're totally shaded, so nothing is absorbing heat. Then, as the seasons change, the amount of sunlight we'll get inside will change appropriately. For example, here's 10:30am on October 5:
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So cool.
The undecided:
At the moment, I have no idea what to look at in terms of supplemental heating and cooling. I believe the solar passive design will do most of the heavy lifting in terms of heating, and ceiling fans and cross ventilation should be mostly sufficient in summer. But there's always long strings of rainy winter days where there's no sun at all, and strings of blistering summer days, to be wary of.
As I stated earlier, I want to avoid any/all ceiling penetrations to minimise air leakage, so that effectively rules out ducted air conditioning.
Budget permitting, I would like a wood fireplace, though that'd be more for occasional use rather than daily use.
Through my research, I think one split system air conditioning unit in the living pavilion should do the trick for any supplemental heating in winter and cooling in summer. That's assuming we do achieve a decent level of air tightness during construction. Possibly, I would put one in the lounge room in the bedroom pavilion as well, which I would think would flow through to most of those bedrooms fairly well. As a bonus, these systems would also be supplemented by the solar if used during the day, if there's any sun at all.
I'm also 50/50 on whether I favour a darker external colour scheme or a lighter one. Originally I was in love with recycled bricks as a feature, coupled with dark standing seam colourbond cladding. But, apparently, a dark roof on a hot day can have effects of an additional 10+ degrees within your roof cavity.
Now I think I may have come around more to the idea of recycled bricks as a feature coupled with horizontal, wide Stria (James Hardie) style cladding in white, with a light coloured roof.
Not sure...
Anyway, I could go on for hours. At this stage, I'm very excited to see what the architect comes back to us with based on the brief we gave him. I welcome any comments, questions, feedback, your experiences with solar passive design... anything at all. Let's nerd out over this
Thylacene
StructuralBIMGuy
Ambedo
